Optical image lens assembly / Largan Precision Co., Ltd.

Title: Optical image lens assembly.Abstract: This invention provides an optical image lens assembly in order from an object side to an image side comprising: a first lens group has a first lens element with positive refractive power; a second lens group has a second lens element with negative refractive power; and a third lens group has at least three lens elements with refractive power; wherein a lens element in the third lens group closest to an image plane has negative refractive power and a concave image-side surface; wherein while a distance between an imaged object and the optical image lens assembly changes from far to near, focusing is performed by moving the second lens group along the optical axis toward the image plane. By such arrangement and focusing adjustment method, good image quality is achieved and less power is consumed. ...

BACKGROUND

The present invention relates to an optical image lens assembly, and more particularly, to a compact optical image lens assembly used in electronic products.

2. Description of the Prior Art

A sensor of a general photographing camera is none other than CCD (charge coupled device) or CMOS device (Complementary Metal Oxide Semiconductor device). In recent years, with the popularity of mobile phones equipped with camera, the demand for compact photographing lenses is increasing. Furthermore, as advanced semiconductor manufacturing technology has allowed the pixel size of sensors to be reduced and compact photographing lenses have gradually evolved toward higher megapixels.

A conventional compact photographing lens equipped in a mobile phone is usually a single focus lens having a fixed focal length. For a specific object distance, since the photographing lens has a limited depth of field, it is apt to produce blurred images. Therefore, as the resolution of compact photographing lenses increases, a focusing adjustment function becomes more and more indispensable as well.

As the system with five lens elements disclosed in U.S. Pat. No. 7,864,454, which is designed to perform focusing by the movement of the whole lens system, has a limited depth of field while focusing at an extremely close site and thereby obtains blur peripheral images resulting in deficiency in image quality. Moreover, as the one disclosed in U.S. Pat. No. 7,777,972; wherein the invention is an image lens system with a structure of two lens groups. However, the second lens group thereof is configured with only three lens elements and thereby the ability to correct aberration and chromatic aberration is not enough.

In addition, generally, a photographing lens with focusing adjustment function performs focusing adjustment by using a driving motor to move the entire photographing lens relative to the sensor. However, such a photographing lens requires higher power consumption because the driving motor is configured to drive the entire photographing lens. Moreover, the photographing lens has a relatively long total track length.

In view of this, there is a constant demand in the industry for an optical image lens assembly, which has a lower driving power consumption of focusing and a better control of the total optical track length thereof.

SUMMARY

The present invention provides an optical image lens assembly comprising, in order from an object side to an image side: a first lens group comprising a first lens element with positive refractive power; a second lens group comprising a second lens element with negative refractive power; and a third lens group comprising at least three lens elements with refractive power; wherein a lens element closest to an image plane in the third lens group has negative refractive power and a concave image-side surface; wherein while a distance between an imaged object and the optical image lens assembly changes from far to near, focusing is performed by moving the second lens group along an optical axis toward the image plane; wherein there are no more than seven lens elements with refractive power in the optical image lens assembly; a focal length of the optical image lens assembly is f, a focal length of the first lens element is f1, and they satisfy the following relations: 0.8<f/f1<2.0.

On the other hand, the present invention provides an optical image lens assembly comprising, in order from an object side to an image side: a first lens group comprising a first lens element with positive refractive power having a convex object-side surface; a second lens group comprising a second lens element with negative refractive power having a concave image-side surface; and a third lens group comprising at least three lens elements with refractive power; wherein a lens element closest to an image plane in the third lens group has negative refractive power, a concave image-side surface and at least one inflection point is form on the image-side surface thereof; wherein the third lens group also comprises a lens element with positive refractive power having a concave object-side surface and a convex image-side surface, which is adjacent to an object-side surface of the lens element in the third lens group closest to the image plane; wherein while a distance between an imaged object and the optical image lens assembly changes from far to near, focusing is performed by moving the second lens group along an optical axis toward the image plane; wherein there are no more than seven lens elements with refractive power in the optical image lens assembly; a difference of the focal lengths of the optical image lens assembly between the second lens element is at the closest and the farthest position to the image plane is Δf, the focal length of the optical image lens assembly is f, and they satisfy the following relations: |Δf/f|<0.1.

By such arrangement and focusing adjustment method, good image quality is achieved and less power is consumed.

The optical image lens assembly of the present invention has the ability to perform focusing by the movements among lens groups, wherein the movable second lens group results in excellent consequence for image quality captured at an extremely close position or an extremely far position. Moreover, since only the second lens group is moved, the power consumption for focusing is less, and it is favorable for a better control of the total optical track length.

In the aforementioned optical image lens assembly, the first lens element has positive refractive power, which thereby can reduce the total track length favorably. The second lens element has negative refractive power, and thereby the aberration of the system can be effectively corrected and the image quality thereof can be favorably improved. When a lens element closest to an image plane in the third lens group has negative refractive power, the high order aberration of the assembly can be effectively corrected. When a lens element, which is adjacent to an object-side surface of the lens element closest to an image plane in the third lens group, has positive refractive power, the total track length of the assembly can be effectively shortened and the sensitivity thereof can be also reduced.

In the aforementioned optical image lens assembly, when the first lens element has a convex object-side surface, the positive refractive power of the lens elements can be strengthened and thereby the total track length of the assembly can be reduced even more. When the second lens element has a concave image lens element, the aberration of the assembly can be corrected favorably. When a lens element, which is adjacent to an object-side surface of the lens element closest to an image plane in the third lens group, is a meniscus lens element with a concave object-side surface and a convex image-side surface, the astigmatism of the assembly can be corrected favorable. When a lens element closest to an image plane in the third lens group has a concave image-side surface, the principle point can be positioned away from the image plane and thereby reducing the total track length of the assembly.

How KEYWORD MONITOR works... a FREEservice from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. Start now! - Receive info on patent apps like Optical image lens assembly or other areas of interest.###

Data source: patent applications published in the public domain by the United States Patent and Trademark Office (USPTO). Information published here is for research/educational purposes only. FreshPatents is not affiliated with the USPTO, assignee companies, inventors, law firms or other assignees. Patent applications, documents and images may contain trademarks of the respective companies/authors. FreshPatents is not responsible for the accuracy, validity or otherwise contents of these public document patent application filings. When possible a complete PDF is provided, however, in some cases the presented document/images is an abstract or sampling of the full patent application for display purposes. FreshPatents.com Terms/Support -g2-0.107

20121018|20120262806|optical image lens assembly|This invention provides an optical image lens assembly in order from an object side to an image side comprising: a first lens group has a first lens element with positive refractive power; a second lens group has a second lens element with negative refractive power; and a third lens group |Largan-Precision-Co-Ltd